1. Field of the Invention
The present invention relates to an exposure apparatus, exposure method, and device fabrication method.
2. Description of the Related Art
When fabricating a semiconductor device or the like by using a photolithography technique, a step-and-scan exposure apparatus is used to transfer the pattern of a mask (reticle) while scanning the mask and the substrate. In order to increase the productivity in such an exposure apparatus, Japanese Patent Laid-Open No. 2011-238707 has proposed a technique of measuring the surface position (height) of a substrate held by a substrate stage while the substrate stage is accelerated (or decelerated).
However, when the surface position of a substrate is measured during acceleration of the substrate stage, the measurement result contains an error (measurement error) because the structure of the apparatus main body and the substrate stage are deformed owing to acceleration of the substrate stage. To solve this, a correction value (offset) for correcting a measurement error is obtained in advance, and a substrate is exposed while a measurement result obtained during acceleration of the substrate stage is corrected based on the correction value.
However, the measurement error changes depending on layout conditions such as the size and arrangement of the shot regions of a substrate and the exposure order of shot regions, and driving conditions such as the speed and acceleration of the substrate stage. Therefore, every time layout conditions and driving conditions are changed, the correction value for correcting a measurement error needs to be obtained.
Deformations (deformation amounts) of the structure and substrate stage change over time owing to a temperature change. The temporal changes of the deformation amounts the structure and substrate stage cause a change of the measurement error contained in the measurement result. Thus, the correction value for correcting a measurement error needs to be obtained again.
In this case, for example, when the correction value is obtained for each shot region, the same time as that of an exposure process for one substrate is required to obtain the correction value, greatly decreasing the productivity.